The present invention relates to door locks and, more particularly, to portable door locks for use independently of the lock generally provided on a door.
Portable door locks, for use in addition to or in place of the conventional lock and key generally provided on a door, have been known in the prior art for sometime. However, many such locks are relatively weak and may be easily damaged when an intruder attempts to break in through the door. In addition, many portable door locks are difficult to apply to and remove from the door, making it hard for an occupant to quickly exit the room in the event of an emergency. There thus remains a need in the art for a portable door lock that is both strong and convenient to use.
The present invention is a portable door lock for use in securing an inward-opening door, thereby preventing intruders from entering an occupied room. The lock of the present invention may be folded when not in use for convenient carrying and storage.
The lock of the present invention comprises a flat bracket having a protrusion which can be inserted into a lock chamber of a doorframe. In a preferred embodiment, the protrusion is U-shaped. The bracket is connected by means of a hinge to a threaded bolt, upon which a hinged brace is slidably mounted. The hinged brace comprises a first member, or leg, which is adapted to be pressed against the door, pivotally connected to a second member, or leg, which is adapted to be pressed against the doorframe. A spring is mounted upon the first member and engages the second member, urging the second member away from the first member. The second member is provided with a stop which engages the first member and prevents the first and second members from pivoting away from each other at an angle greater than about 60xc2x0. A thumbwheel is mounted upon and threadably engages the threaded bolt, effectively retaining the hinged brace upon the threaded bolt.
When the protrusion is inserted in the lock chamber and the door is closed, the thumbwheel can be screwed down the threaded bolt towards the bracket. This urges the hinged brace towards the door and doorframe, pressing the first member against the door and the second member against the doorframe. The thumbwheel can then be tightened by hand, effectively locking the door. The inventive door lock can be quickly removed from the door by simply loosening the thumbwheel and spinning it up the threaded bolt away from the door.
The first member of the hinged brace is sized to fit within the second member and is also recessed to accept the threaded bolt when the hinged brace is closed by urging the first and second members together. In addition, the first and second members are shaped to form a slot positioned to accept and retain the protrusion in the bracket when the hinged brace is closed and the bracket is folded towards the threaded bolt. The inventive door lock can thus be folded simply by closing the hinged brace and folding the bracket towards the threaded bolt. The lock can then be held in this folded position by tightening the thumbwheel against the closed hinged brace.
In an alternative embodiment, the threaded bolt and thumbwheel may be replaced by a rod and locking member, the locking member being mounted upon the rod and being capable of locking to the rod at multiple positions along the rod.
The door lock of the present invention offers several advantages over previous portable door locks. As detailed below, due to the design of the lock, the force exerted on the door by someone attempting to enter the room is transferred to the doorframe where it counters the force exerted by the protrusion on the lock chamber. Furthermore, due to the hinge linkage between the bracket and the threaded bolt, no torsional stresses are placed on any of the components of the lock. The inventive lock is thus able to withstand the application of large forces to the outside of the door.
The lock is easy to use and can quickly be applied to or removed from a door. Due to the pivotal connection between the first and second members of the hinged brace, the lock is able to automatically adapt to differences in depth between the door and door frame. The lock may also be easily folded and held in a folded position for convenient carrying.
The above-mentioned and additional features of the present invention and the manner of obtaining them will become apparent, and the invention will be best understood by reference to the following more detailed description, read in conjunction with the accompanying drawings.